Scotch yoke engine

ABSTRACT

The invention relates to a scotch yoke fluid device ( 10 ). The scotch yoke fluid device ( 10 ) has a crank ( 11 ) with a big end having an axis ( 14 ) which orbits around a main axis ( 15 ) for the crank ( 11 ). Connecting means ( 13 ) are mounted on the big end axis ( 14 ). There is at least one piston ( 22 ) mounted for reciprocating motion in a cylinder ( 18 ) along a piston axis. The piston has a cross-sectional area perpendicular to the piston axis. The piston also has guide means ( 16 ) which include a linear surface transverse to the piston axis. The guide means ( 16 ) engage engagement means on the connecting means. There is at least one restricting means ( 24 ) for constraining the piston ( 22 ) to move along the piston axis. The restricting means ( 24 ), or a constraining means ( 19 ) for the restricting means ( 24 ), or both, always extend into a volume defined by the swept area of the crank ( 11 ), projected along the main axis ( 15 ) of the crank ( 11 ). The invention also provides components, such as pistons, piston rods, restraining means and constraining means, made of composite fibre. The composite fibre may include both aligned and non-aligned material. The invention also relates to methods of manufacturing such components.

TECHNICAL FIELD

[0001] This invention relates to improvements in engines and in enginecomponents. The invention particularly relates to engines of the scotchyoke type and to components therefor.

BACKGROUND ART

[0002] In a first aspect, the present invention deals with a developmentof an aspect of one of the inventions disclosed in International PatentApplication No. PCT/AU00/00281. The invention in that disclosure relatedto a fluid device which included a crank having a big end with its axisorbiting around a main axis. Connecting means was rotatably mounted onthe big end axis. At least one piston, being mounted for reciprocalmotion in a cylinder along a piston axis, had piston guide meansengaging engagement means on the connecting means. Also included was atleast one restricting means for constraining the piston to move alongthe piston axis. In a preferred embodiment, as the crank mechanismrotated, the restricting mews extended into the swept volume of thecrank, projected along the main axis of the crank.

[0003] In the original invention as disclosed in PCT/AU00/00281, thepiston guide means was commonly a surface which slidably engaged anothersurface, often complementary, on the connecting means. The restrainingmeans was conveniently parallel to the piston axis and was described asextending into the swept volume of the crank mechanism, at least whenthe piston was at bottom dead centre.

[0004] In a second aspect, the present invention deals with themanufacture of components suitable for use in connection with the scotchyoke devices in PCT/AU00/00281, as well as other forms of scotch yokeengine, and also in connection with the first aspect of the presentinvention.

[0005] It is possible to make the components of the inventions referredto from traditional materials, especially, in many cases, aluminiumalloy. However, more recently inventions have been made with a view tomanufacturing pistons from carbon-carbon material. There are significantadvantages in that carbon-carbon components can have a higher meltingpoint than aluminium alloy, for example and may retain room temperaturestrength to higher temperatures. They can be made lighter than aluminiumcomponents and have an extremely low co-efficient of thermal expansion.

[0006] Imported herein by reference is the content of the following USpatent specifications dealing with carbon-carbon technology: 4,683,809,4,909,133, 5,900,193 and 6,029,346 and 6,148,785.

[0007] U.S. Pat. No. 4,683,809 is concerned with the manufacture of acarbon-carbon piston involving inserting precursor fibres in a mat orrandom fibre orientation in a closed die, pyrolizing the precursorfibres, impregnating them with a cabonaceous resin system, stretchingthe precursor fibre prior to or during stabilisation, stabilising thematerial by heating the fibre in air, carbonising the material by slowlyheating the fibre in an inert atmosphere and graphitizing the fibres byraising the temperature to a desired beat treatment temperature. Thepiston can be fitted to a cylinder by lapping so as to precisely fit thebore of the cylinder. The piston may be constructed without pistongrooves and without reinforcing material. The piston crown area may bereinforced with unidirectional fibres or cloth.

[0008] U.S. Pat. No. 4,909,133 discloses an improvement over theinvention in 4,683,809, in which the crown, side wall, skirt and innersurfaces of the piston are armed by a one piece, closed end, singleknitted fibre structural shape. It is claimed that a knitted fibrearchitecture, which enables the fibre directions to be controllable,results in increased strength properties, compared to cloth or mat.

[0009] U.S. Pat. No. 5,900,193 is concerned with a method of makingcarbon-carbon composite pistons by stacking carbon fibre laminae,prepregnated with a carbonaceous resin, over male mandrels to form alaminated composite billet, compressing female mandrels into thelaminated composite billet to form a mould assembly, heating thelaminated composite billet in the mould assembly to cure thecarbonaceous resin, pyrolizing the composite billet to carbonise it,reimpregnating the carbonised composite billet with additionalcarbonaceous resin, repyrolizing to further density the billet andcoring piston blanks, each with a crown and complete piston skirtsurface, from the densified billet. The machined blanks can then bemachined to final dimensions. The carbon fibre laminae may be wovencarbon fabrics, unidirectional car fibres or directionally oriented totailor structural and thermal properties. Optionally, ring grooves maybe machined into the pistons. As an additional option, the crown andskirt surfaces of the piston blanks may be sealed, for example, with aceramic coating or a metallic coating.

[0010] Further modifications are disclosed in U.S. Pat. No. 6,029,346.

[0011] Still further modifications are disclosed in U.S. Pat. No.6,148,785.

[0012] The second aspect of this invention is concerned withimprovements in making components of scotch yoke devices, includingthose disclosed in PCT/AU00/00281. In one particular aspect, the presentinvention is concerned with making a combined piston and connecting rodor connecting means using carbon-carbon composite or other fibrecomposite.

DISCLOSURE OF THE INVENTION

[0013] In relation to the first aspect of the invention, it has now beenfound that it is advantageous and possible to design the fluid engine sothat the restraining means can extend into the swept volume of the crankmechanism, even when the piston is at top dead centre.

[0014] The restraining means will usually engage a complementaryconstraining means, usually mounted on the crank case. In the presentinvention, these constraining means may extend into the swept volume ofthe crank mechanism. In this invention, either the constraining meansextends into the swept volume of the crank mechanism or the restrainingmeans so extends, or both may so extend

[0015] Accordingly, in the first aspect, the present invention providesa scotch yoke fluid device which includes:

[0016] a crank including a big end having an axis which orbits about amain axis for the crank;

[0017] connecting means mounted on the big end axis;

[0018] at least one piston mounted for reciprocal motion in a cylinderalong a piston axis, the piston having a cross-sectional areaperpendicular to the piston axis, the piston having guide meansincluding a linear surface transverse to the piston axis, the guidemeans engaging engagement means on the connecting means; and

[0019] at least one restricting means for constraining the piston tomove along the piston axis;

[0020] wherein the piston guide means bisects the piston cross-sectionalarea and at least part of each restricting means is located within avolume defined by the piston cross-sectional area projected along thepiston axis, but is not located along the centre line of the bisectionformed by the piston guide means,

[0021] characterised in that at least one of:

[0022] i) the or at least one of the restricting means; and

[0023] ii) a constraining means for the or at least one of therestricting means

[0024] always extends into a volume defined by the swept area of thecrank projected along the main axis of the crank.

[0025] The contents of International Patent Application No.PCT/AU00/00281 are imported herein by reference. The variations of theinvention disclosed in the imported specification may apply equally tothe first aspect of the present invention.

[0026] Preferably, the restraining means fits into a groove or channelof the constraining means, which in turn is formed in or bolted to thecrank case. The constraining means may comprise or include one or morerollers.

[0027] In this specification, when the restraining means or theconstraining means is described as extending into the swept volume ofthe crank mechanism, it is to be understood that this includes thesituation where the restraining means and/or the constraining means, asthe case may be, meets the circumference of the swept volume of thecrank mechanism, as well as when that circumference is crossed.

[0028] The invention disclosed in the specification imported herein byreference, above, is capable, in some embodiments, of variablecompression. It is within the scope of this invention that theconstraining means may be relocatable to accommodate the variablecompression embodiment. For example, the constraining means may beadapted to be unbolted from the crank case and relocated in a moreappropriate position on the crank case.

[0029] It will also be appreciated that, while this aspect of theinvention has been illustrated with regard to a fluid device having asingle piston, it is anticipated that this aspect of the invention maybe applicable to multi-piston fluid devices.

[0030] In the second aspect of the present invention, to the varioustypes of fibre structure disclosed in the US specifications, it isproposed to add non-aligned material, such as carbon, to alignedmaterial and/or to add chopped strand tape. These may be mixed into theresin. The addition of chopped stands may provide compression loadstrength in addition to the previously-disclosed advantages. This canreduce the possibility of the composite bursting under pressure.

[0031] The second aspect of the invention relates to components,especially pistons, connecting means, restraining means, constrainingmeans and combined pistons and connecting means. Such components may besuitable for any type of scotch yoke device, including but not limitedto those disclosed in PCT/AU00/00281.

[0032] The components may be made of any of the materials disclosed inthe US specifications referred to above and may optionally includenon-aligned material and/or chopped strand tape.

[0033] The invention includes various novel methods of making suchcomponents. Specific examples of these are given in connection with thedescription relating to the drawings, below. As will be appreciated by aman skilled in the art, each of these specific examples can beextrapolated to a general method of manufacture and the invention coversthese extrapolations.

[0034] The second aspect of the present invention is suitable for theapplication of pultrusion, an automatic method of producing continuingfibre reinforced shapes in large volumes. The process of pultrusion isknown in the art.

[0035] Using pultrusion, and incorporating it in the second aspect ofthis invention, it is feasible to make pistons end to end, like a chainof sausages, the pistons being severed one from the other at the finalstage of manufacture. In this embodiment, the fibre strands may bepulled along through the die mould prior to injection of resin, so thatthe fibre sods are oriented in the desired direction.

[0036] In another embodiment, the fibres used are chosen from, but notlimited to, the following list: kevlar, carbon, copper strands, glass,plastic, aramids or combinations of various fibres or any other suitablereinforcing material, the strands being held together in any suitableway. Preferably, the strands are pre-stressed then impregnated withresin. The resin used may be any suitable material known to the art.Fibre reinforced aluminium, particularly carbon fibre reinforcedaluminium, can be manufactured so as to be lighter than aluminium alloy.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The invention in its aspects will be now described in connectionwith certain non limiting preferred embodiments thereof, described inconnection with the drawings, in which:

[0038]FIG. 1 is a sectional side elevation of an embodiment of a fluidengine device according to the first aspect of the invention;

[0039]FIG. 2 is a view of the device of FIG. 1, looking in the directionof arrow A;

[0040]FIG. 3 is a variation of the embodiment of FIG. 1;

[0041]FIG. 4 is a further embodiment of the first aspect of theinvention, showing a sectional side elevation of a second embodiment—“aboxer” type device;

[0042]FIG. 5 is a side elevation of a connecting means made according toa first embodiment of the second aspect of the invention;

[0043]FIG. 6 is a side elevation of one of the components in FIG. 5;

[0044]FIG. 7 is a similar view to that of FIG. 5, but showing theconnecting means having a passage for oil or other fluid;

[0045]FIG. 8 shows how components may be formed from a composite billetof carbon-carbon or other fibre;

[0046]FIG. 9 is a view in a plane 90° to the view of FIG. 5;

[0047]FIG. 10 shows a component of FIG. 11, which represents a variationof FIG. 9;

[0048]FIG. 12 is a side view of the element of 10;

[0049]FIG. 13 is a further variation of the embodiment in FIG. 9;

[0050]FIG. 14 is a perspective view of an element similar to that inFIGS. 9 to 13;

[0051]FIGS. 15, 16 and 17 illustrate the addition of being surfaces tocomponents made from carbon-carbon or other fibre;

[0052]FIGS. 18, 19, 20, 21, 22 and 23 are different alternatives to theembodiment in FIG. 5;

[0053]FIG. 24 is a perspective view, showing a formed composite billetand indicating how different components may be carved out of the billet;

[0054]FIG. 25 shows one of the carved out components from FIG. 24;

[0055]FIG. 26 is a side view of a component similar to that in FIG. 25;

[0056]FIG. 27 is an end view of the component of FIG. 26;

[0057] FIGS. 28 to 36 are further embodiments, alternative to that inFIG. 5;

[0058]FIG. 38 is a perspective view of a connecting means or connectingrod which in this case can combine restraining guide means;

[0059]FIG. 39 is another version of a piston and connecting means;

[0060]FIG. 40 is a further version of a piston incorporating first andsecond piston guide means;

[0061]FIG. 41 is a representation of one of the parts in FIG. 40;

[0062]FIG. 42 shows a version of a cylinder head, connecting rod andfirst piston guide means (slider) shown in two pieces;

[0063]FIG. 43 is a top view of the embodiment in FIG. 42, assembled;

[0064]FIG. 44 shows a carbon-carbon or other fibre billet after a pistonhead, such as that shown in FIG. 42, has been carved out;

[0065]FIG. 45 shows, assembled, a piston head and connecting means madeup of several pieces, some of which are shown in FIG. 46;

[0066]FIG. 47 shows an alternate way of making the piston head of FIG.46;

[0067]FIG. 48 is a view of a connecting means varying slightly from thatin FIG. 38;

[0068]FIGS. 49, 50 and 51 show (in part) different ways of joining theembodiment in FIG. 48;

[0069]FIGS. 52 and 53 are alternate embodiments for the connecting meansof FIG. 49;

[0070]FIG. 54 is an end view of a solid extruded connecting rod;

[0071]FIG. 55 is an end view of the embodiment in FIG. 53, showing aparticular orientation of fibre;

[0072]FIG. 56 is an alternate embodiment (in part) to that of FIG. 40;

[0073]FIG. 57 is another embodiment of the connecting means of FIG. 48,but being differently shaped on the end remote from the piston head;

[0074]FIG. 58 is another embodiment of the arrangement in FIG. 5;

[0075]FIG. 59 is a top view of the embodiment in FIG. 58;

[0076]FIG. 60 is a perspective view of a billet from which connectingmeans such as those in FIG. 48 may be cut;

[0077]FIG. 61 shows a connecting means cut from the sheet of FIG. 60;

[0078]FIG. 62 shows a different version of an element cut from a sheetlike FIG. 60;

[0079]FIG. 63 shows in end view a sheet or billet before the element ofFIG. 62 (which includes a piston head) is cut out;

[0080]FIG. 64 shows how a sheet or billet like that of FIG. 60 may bemanufactured in a tube form instead of “flat”;

[0081]FIGS. 65, 66, 67 and 68 show different ways of cutting up sheetsor billets to form components of the second aspect of the invention;

[0082]FIG. 69 shows in perspective view a solid cylinder ofcarbon-carbon or other material and shows has piston heads may be cutout;

[0083]FIG. 70 shows an alternate way of cutting cylinder heads out of abillet and represents an alternate to the illustration in FIG. 8,

[0084]FIG. 71 shows a cylinder head having been cut out of a carved outsquare of the billet of FIG. 70;

[0085]FIG. 72 shows a “chain” of pistons prior to cutting out of acontinuous billet;

[0086]FIG. 73 shows a perspective view of a piston head made up of aseries of laminations;

[0087]FIG. 74 is the piston head of FIG. 73 in exploded form;

[0088]FIG. 75 is an end view of a piston bead similar to that in FIG.46;

[0089]FIG. 76 shows some of the components of FIG. 75;

[0090]FIG. 77 illustrates an embodiment of a method of wrapping fibretape around a piston head, such as that in FIG. 45;

[0091]FIG. 78 shows an alternative wrapped piston head,

[0092]FIG. 79 shows the wrapping of the fibre tape without picturing thepiston head, for ease of illustration;

[0093]FIG. 80 is a diagrammatic view of the wrapping procedure in FIG.79 after several turns have been made;

[0094]FIG. 81 is a further embodiment of a piston, alternative to thatin FIG. 5;

[0095]FIG. 82 is a plan view of the piston of FIG. 81;

[0096]FIGS. 83, 84 and 85 are alternate versions of the piston of FIG.82;

[0097]FIGS. 86, 87 and 88 show a piston head, connection means andconnecting means, respectively, adapted to the slotted together and;

[0098]FIGS. 89, 90 and 91 show corresponding components in a differentconfiguration.

BEST MODE OF CARRYING OUT THE INVENTION

[0099] In FIGS. 1 and 2, fluid device 10 has a crank mechanism 11including a big end bearing 12. Big end bearing 12 orbits about mainaxis 15 and has a big end axis 14. Rotatably mounted on big end bearing12 is connecting means 13 which is engaged by first piston guide means16.

[0100] Piston 22 is mounted for reciprocal motion in cylinder 18 (referFIG. 1). Piston 22 includes intermediate means 20 to which piston guidemeans 16 are attached.

[0101] The restraining means are shown at 24 and can be see from FIG. 2.These extend into the swept volume of crank mechanism 11, even whenpiston 22 is at top dead centre as shown in FIGS. 1 and 2.

[0102] Restraining means 24 are constrained by constraining means 19which, as illustrated, may also extend into the swept volume of crankmechanism 11.

[0103] Constraining means 19 may of course be of a differentconfiguration so as to provide more extensive engagement of secondpiston guide means 24.

[0104] Constraining means 19 are conveniently bolted to the crank case(not shown).

[0105] As can be seen from FIG. 3, constraining means 19 can be of alarger dimension compared to that in FIGS. 1 and 2.

[0106] With reference to FIG. 4, while this shows an alternativeembodiment, the basic intention is the same as that shown in thepreceding figures. The constraining means 19, in the case of each of theopposed pistons shown, extends into the swept volume of the crank. Itwill be appreciated that, in the embodiment shown in FIG. 4, the pistonat the left hand side is shown at top dead centre while the piston atthe right hand side is shown at bottom dead centre.

[0107] Reference is now made to the second aspect of the invention andto the remaining figures.

[0108] As a preliminary, the contents of international patentapplication No. PCT/US99/02153 are imported herein by reference. Thisspecification discloses friction materials which can be used inconnection with this second aspect of the invention, particularly ascoatings or as component parts.

[0109] In the Figures, for ease of reference similar parts will be giventhe same reference numerals. It is anticipated that for mostapplications all of the parts illustrated may be made from carbon-carbonor other fibre composites.

[0110] Referring to FIG. 5, connecting means 31 has engagement surface33 and connection means 34, which in turn is joined to connection means36. In this embodiment, connection means 34 is joined to connectionmeans 36 via bolt 39. Connecting means 31 and connection means 34 aremade in one piece from carbon-carbon composite. A mixture of fibre typesis used As can be seen from the Figure, long strands 40 lie in the planeof the drawing. Other long strands 42 are perpendicular to the plane ofthe drawing. Mixed chopped strands 44 are also shown. This configurationis also shown in FIG. 6, which is a cross sectional view of connectionmeans 36 in FIG. 5.

[0111] As shown in FIG. 7, the components may include a passage 46 foroil or other fluid.

[0112] Pistons 30 may be cut out of a billet 48 of suitably layeredmaterial, with pistons 30 being carved out in any suitable way (referFIG. 8). The caring out may be carried out by any suitable method,including sawing, laser cutting, pressure cutting, projectile cutting,etc.

[0113] Turning now to FIG. 9, which shows a cross sectional side view ofconnection means 36 in FIG. 5, it can be seen that connection means 36is, made in two annexed parts.

[0114] Referring now to FIG. 9, it will be appreciated that thiscomponent 36 can be carved out of a slab billet. The components 36 maybe joined together in any suitable way, such as shown in FIG. 9 or byusing a joining plate 50 which may contain two pins 52 as in FIG. 11 orfour such pins as in FIG. 13. Six such pins are shown in FIG. 9. Big endcap 54 is shaped suitably in each case. Big end cap 54 may be made ofthe carbon-carbon or other fibre material, as can the other components,including connection means 36.

[0115] Turning now to FIGS. 15, 16 and 17, these Figures illustratingthe addition of different bearing surfaces to engagement surface 33 and,in the case of FIG. 17, to part of connection means 34. In FIG. 15, beansurfaces 56 are attached to the upper and lower parts of engagementsurface 33 and will provide for tensile and compressive thrust. In FIG.16, bearing surfaces 56 also extend part way down the sides ofengagement surface 33, thus allowing for side thrust also. This issimilarly the case with the FIG. 17 embodiment. In addition, in the caseof the FIG. 17 embodiment, further bearing surfaces 58 are fitted asshown in two pieces in each case on connection means 34 so as to providebearing surfaces for a bolt 39. Bearing surfaces 58 can be riveted on,for example.

[0116] In each of FIGS. 15 to 17, the bearing surfaces may be glued onand may be metal, carbon-carbon fibre or other material. Bearingsurfaces 58 preferably dove tail or otherwise fit together to provide asmooth bearing surface.

[0117] FIGS. 18 to 20 show connection means 34 in variousconfigurations, in each case bonded or otherwise joined to connectionmeans 36.

[0118] In FIGS. 21, 22 and 23, engagement surfaces 33 are shown joinedto connection means 34. In the case of the embodiments in FIGS. 21 and22, connection means 34 are joined to connection means 36 which may bein one piece (FIG. 21) or two pieces (FIG. 22). However, in FIG. 23,connection means 34 is integral with connection means 36.

[0119] Turning now to FIG. 24, there is shown billet 48 in this casemoulded into a particular cross sectional shape which can be carved outto result in component 60 as shown in FIG. 25. In a similar way, thecomponents in FIGS. 26 and 27 can be carved out of a suitably shapedbillet 48.

[0120] With reference to FIGS. 28 to 37, these show various differentembodiments of connecting means 31, in each case having engagementsurface 33, connection rod 34, and connection means 36. In the FIG. 32embodiment, for example, the component parts forming surface 33 and rod34 may be glued or bolted together. In the FIG. 36 embodiment, rod 34 isjointed to connection means 36 by post 62. In the FIG. 37 embodiment,surface 33 is laminated, laminations being glued together and rod 34 ishollow internally, to result in a lighter component having greaterstruck strength.

[0121] In the embodiment in FIG. 38, it will be noted that theembodiment includes oil passages 46. Alternately, these can representreinforcement, such as bolts extending the length of the rod 34. It willalso be noted that in this case the rod 34 can include restring means24.

[0122]FIG. 39 is a fierier embodiment of connecting means 31 and isself-explanatory.

[0123] Piston 30 is FIG. 40 includes restraining guide means 24 andpiston guide means 16.

[0124] Restraining means 24 can be made as shown in FIG. 41.

[0125] In FIG. 42 there is shown piston 30 which can be made integrallywith rod 34 or separately from it. Connection means 36 is manufacturedwith extension 60 adapted to fit into cavity 66.

[0126] In FIG. 49, billet 48 has had carved out of it piston head 32,leaving a cavity 68.

[0127] Turning now to FIGS. 45 and 46, head 32 is made of four parts 70.(Of course, there could be more or less parts than four). These arefitted into cross-shaped connecting rod 34. An alternative as shown inFIG. 47 is for parts 70 to be made in halves, rather ta in quarters asshown in FIGS. 45 and 46.

[0128] The embodiment in FIG. 48 shows connection rod 34 beingstrengthened by pieces 72, each of which may be cut out of a flatcarbon-carbon composite sheet, trimmed and glued into place.

[0129] In FIGS. 49 to 51, the component parts of connection rod 34 areshown in totality, or as one half of the connecting rod 34, in each casethe drawing being repeated and mirror reversed to provide the otherhalf. Thus connection rod 34 is made up of components 34 a and 34 b,with the optional omission of pieces 72.

[0130] Different configurations are shown in FIGS. 52 and 53, which areself-explanatory, as is FIG. 54.

[0131] As shown in FIG. 55, the connecting rod in FIG. 53 can be made upof strands 40, 42 and 44. (Any of 40, 42 and 44 may be used, separatelyor in combination).

[0132] If desired, the embodiment in FIGS. 53 and 55 may be cut out of asingle sheet in one piece.

[0133] The embodiments in FIGS. 56 to 59 are self-explanatory.

[0134] Turning now to FIG. 60, billet 48 may be cut to form connectingrods 34 as shown in FIG. 61 by slicing at cut lines 74.

[0135]FIGS. 62 and 63 are self-explanatory.

[0136]FIG. 64 shows a billet 48 similar to that in FIG. 60, except thatinstead of a “flat” sheet, a tube is formed.

[0137] In FIGS. 65 to 69, billet 48 is cut—as shown in some cases, alongcut lines 74 to form suitably-shaped elements. For example, in FIG. 69the solid cylinder can be cut to form piston heads 32.

[0138]FIG. 70 is somewhat similar to the illustration in FIG. 8, exceptthat in this case billet 48 has cut out of it in a grid pattern pistonheads 32.

[0139]FIG. 72 is self-explanatory.

[0140] In the embodiment of piston head 34 shown in FIGS. 73 and 75, thepiston head is made of thee different laminates A, B and C, which arebonded together by suitable means.

[0141]FIGS. 75 and 76 represent a development of the piston in FIGS. 45and 46, except in the case of FIGS. 75 and 76 there are six parts 70 ofhead 32. Further, head 32 is wrapped by tape 76.

[0142]FIG. 78 shows a simplified version of a wrapped piston head 32. Towrap piston head 32, a strand of fibre tape 80 is wound around part 70of head 32 as shown in FIGS. 77, 79 and 80.

[0143] FIGS. 81 to 85 are self-explanatory.

[0144]FIGS. 86, 87 and 88 show in detail how an embodiment such as thatin FIG. 83 may be slotted together with suitable grooves 80 in pistonhead 84 and connection means 36. Similarly, FIGS. 89, 90 and 91 show thefitting together of the piston components similarly to those in FIG. 42.

INDUSTRIAL APPLICABILITY

[0145] The present invention takes the invention disclosed inPCT/AU00/00281 and further improves it both in relation to theconfiguration of the restricting means and/or constraining means and inrelation to the composition of the components, especially combinedpistons/connecting means. The present invention enhances the existingindustrial applicability of the invention in PCT/AU00/00281. It alsomakes advances in the manufacture of scotch yoke device componentsgenerally.

1. A scotch yoke fluid device which includes: a crank including a bigend having an axis which orbits about a main axis for the crank;connecting means mounted on the big end axis; at least one pistonmounted for reciprocal motion in a cylinder along a piston axis, thepiston having a cross-sectional area perpendicular to the piston axis,the piston having guide means including a linear surface transverse tothe piston axis, the guide means engaging engagement means on theconnecting means; and at least one restricting means for constrainingthe piston to move along the piston axis; wherein the piston guide meansbisects the piston cross-sectional area and at least part of eachrestricting means is located within a volume defined by the pistoncross-sectional area projected along the piston axis, but is not locatedalong the centre line of the bisection formed by the piston guide means,characterised in that at least one of: i) the or at least one of therestricting means; and ii) a constraining means for the or at least oneof the restricting means always extends into a volume defined by theswept area of the crank projected along the main axis of the crank. 2.The fluid device of claim 1, wherein the constraining means includes agroove or channel into which the restraining means fits.
 3. The fluiddevice of claim 2, wherein the constraining means is formed in or boltedto a crank case.
 4. The fluid device of claim 1, wherein the restrainingmeans and/or the constraining means meets the circumference of the sweptvolume of the crank.
 5. The fluid device of claim 1, wherein therestraining means and/or the constraining means crosses thecircumference of the swept volume of the crank.
 6. The fluid device ofclaim 1, wherein the constraining means is relocatable.
 7. The fluiddevice of claim 1, wherein the constraining means includes or comprisesone or more rollers.
 8. The fluid device of claim 1, having more thanone piston.
 9. The fluid device of claim 1, wherein the or at least onepiston is combined with the connecting means.
 10. The fluid device ofclaim 9, wherein the combined piston and connecting means is composed ofa fibre composite.
 11. The fluid device of claim 10, wherein the fibrecomposite includes non-aligned material and/or chopped strand tape. 12.The fluid device of claim 10, wherein the fibre composite is acarbon-carbon composite or a composite using fibres chosen from thegroup: kevlar carbon, copper strands, glass, plastic or a combination oftwo or more of the foregoing.
 13. The fluid device of claim 12, whereinthe non-aligned material and/or chopped strand tape is mixed withaligned material into a resin.
 14. The fluid device of of claim 10,wherein the fibre composite also includes metal.
 15. The fluid device ofclaim 14, wherein the metal is aluminium.
 16. A scotch yoke fluid devicewhich includes: a crank including a big end having an axis which orbitsabout a main axis for the crank; connecting means mounted on the big endaxis; at least one piston mounted for reciprocal motion in a cylinderalong a piston axis, the piston having a cross-sectional areaperpendicular to the piston axis, the piston having guide meansincluding a linear surface transverse to the piston axis, the guidemeans engaging engagement means on the connecting means; and at leastone restricting means for constraining the piston to move along thepiston axis; wherein the piston guide means bisects the pistoncross-sectional area and at least part of each restricting means islocated within a volume defined by the piston cross-sectional areaprojected along the piston axis, but is not located along the centreline of the bisection formed by the piston guide means, characterised inthat the or at least one piston is combined with the connecting means.17. The fluid device of claim 16, wherein the combined piston andconnecting means is composed of a fibre composite.
 18. The fluid deviceof claim 17, wherein the fibre composite includes non-aligned materialand/or chopped strand tape.
 19. The fluid device of claim 17, whereinthe fibre composite is a carbon-carbon composite or a composite usingfibres chosen from the group: kevlar carbon, copper strands, glass,plastic or a combination of two or more of the foregoing.
 20. The fluiddevice of claim 19, wherein the non-aligned material and/or choppedstrand tape is mixed with aligned material into a resin.
 21. The fluiddevice of of claim 17, when the fibre composition also includes metal.22. The fluid device of claim 21, wherein the metal is aluminium.
 23. Acomponent suitable for a scotch yoke fluid device including the deviceof claim 1 or 16, the component being composed of a fibre composite. 24.The component as claimed in claim 23, wherein the fibre compositeincludes non-aligned material and/or chopped strand tape.
 25. Thecomponent of claim 23, wherein the fibre composite is a carbon-carboncomposite or a composite using fibres chosen from the group: kevlarcarbon, copper strands, glass, plastic or a combination of two or moreof the foregoing.
 26. The component of claim 25, wherein the non-alignedmaterial and/or chopped strand tape is mixed with aligned material intoa resin.
 27. The composite of of claim 23, wherein the fibre componentalso includes metal.
 28. The component of claim 27, wherein the metal isaluminium.
 29. (Cancelled)
 30. (Cancelled)
 31. (Cancelled)